Cellular respiration is the process by which cells in plants and animals break down sugar and turn it into energy, which is then used to perform work at the cellular level. The purpose of cellular respiration is simple: it provides cells with the energy they need to function. If living things could not get the energy they need out of food, it would be absolutely worthless. All living things would eventually die, no matter the quality and amount of food.
C6H12O6 + 6O2 → 6CO2 + 6H2O (glucose + oxygen -> carbon dioxide + water)
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Motor unit refers to the functional element of muscle contraction during an exertion. There are two basic types of motor unit: large and small motor units. During low to moderate level exercise, small motor units are activated. Small motor units are recruited during sustained activity; is made up of high proportion of type 1 muscle fibers, which are resistant to fatigue